火电厂大气污染物自动监测达标判定现状与国际经验借鉴

Present Situation and International Experience of Using Continuous Emissions Monitoring to Assess the Compliance with Emission Limit Values of Air Pollutants for Thermal Power Plants

近年来,我国火电厂具有启停频繁、日内工况波动大、平均负荷低的生产特点,在当前经济技术条件下,小时等短时长内不可避免地会出现高排放浓度。自动监测小时浓度数据直接采用《火电厂大气污染物排放标准》(GB 13223—2011)限值进行达标判定,易引发"普遍性违法"。欧盟、美国相关排放标准采取了长期尺度严格执行标准限值,中短期尺度允许小概率超过标准限值一定倍数,并设定达标考核豁免条件的做法。采用欧盟、美国相关排放标准的考核方法后,2014年7月1日—2015年4月25日某省火电厂烟尘、SO_2、NO_x小时浓度100%达标排口比例由不足60%提升至80%以上。这种长期严格、短期放宽的考核方法更符合我国火电行业生产特点,对完善火电厂自动监测达标判定规则有重要参考价值。

Recently thermal power plants in China have the production characteristics of frequent starts and stops, great intraday fluctuation of operation condition, and low average load. Furthermore, under the current technical and economic condition, emissions with high concentration within a short period of time may occur inevitably. As a consequence, applying GB 13223-2011 limit values to directly assess the hourly concentration data obtained from continuous emissions monitoring system might easily lead to ＂ general illegality＂. Adopt the strict enforcement of related emissions standards in both the European Union （EU） and the United States （ U. S. ） from a long-term scale; allow limit-exceeding by certain multiple at small probability from a medium-to-short-term scale; and set criteria for assessment exemption conditions. Employing the assessment methods from the EU and U, S. from July 1 , 2014 to April 25, 2015, the compliance of hourly emissions concentration of dust, SO2 and NO in the plants of the province increased from less than 60% to 80% or more. The assessment method, which is strict at long-term while relatively relax at short-term, accords with the production characteristics of China＇ s thermal power industry. More importantly, it is of great reference value to improve the rules to assess the compliance of continuous emissions monitoring in thermal power plants.